Method of covering balls



April 1950 F. T. ROBERTS 2,505,430

METHOD OF COVERING BALLS Filed May 3, 1945 3 Sheets-Sheet 1 (o p o (a (a {a Q A? o 5 f Q, 4

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April 25, 1950 F. T. ROBERTS 2,505,430

' METHOD OF COVERING BALLS Filed May 3, 1945 '3 Sheets-Sheet 2 fig-7 IN VEN TOR. Q g ns-0 7T Fonz-er:

April 25, 1950 F. T. ROBERTS I 2,505,430

METHOD OF COVERING BALLS Filed May 3, 1945' 3 Sheets-Sheet 3 IN V EN TOR. FEED 7T 1P0 65/975 Patented Apr. 25, 1950 UNITED STATES PATENT OFFICE METHOD OF iCOVERING==BALLS Fred Thomas Roberts, Ridgefi'eli'Conn.

Application May- 3, 1945,:Se'rial'No. 591;7'87

9 Claims. L1

This invention relates to :a "system :of covering tennis 'and like balls. Heretofore it has been the custom to apply manually two 8- shaped covers cem-ented to the exterior of a :previously formed and inflated ball, the *edges of the two cover members ad'i'oining. :An o'bjectof my 'invention is to reduce the manual operation "to a minimum, and 'cover the ball im'or'e :accurately and at l'ess "expense.

M'o'st tennis 'balls are first made as'a completed rubber ball; molded and inflated to the correct size for covering, "and then the :tcovers of molten are attachedby hand, *the covers tbeing iirst :cut in the conventional figur'e "'8 pieces. "These figure 8 covers areusuallydiedout'ofialayer-of melton, to one face ofwhich icement has been previously applied, and are ithen stacked'together and the edges cemented while in the stack. They "are then separated: and attahed to the surface of the ball by hand. Greatskill is required to get "the covers on straight'andwithout Wrinkles, 'an'd'the edges are cemented together with the cement previously put on the pieces while they were stacked together.

Due to the fact that theball, covered as above described, is then given a vulcanization "to set the cement, "there is a shrinkage of 'the melton cover, so an allowance is made for this shrinkage, the cover'being cut with a fullness, andthis adds to the difficulty of properly applying the covers 5 and joining their edges.

- 'In ordinary practice, the balls "after being in this manner covered are put in a mold having cavities of the correct size, the mold closed and vu'lcanizi'ng heat "applied, the heat generating enough additional pressure so that the cover "is ironed out smoothly.

"The heat and pressure usually employed mats the wool fibers down on 'the ball, and it is'necessary to resort to additional operations to "fluff up "the material, which isusual'ly done'by tumbling the balls in live steam after they are completed. In .my process, I amfiable to use air-curing to vulcanize the cover in place and thereby eliminate "this subsequent step.

'Myprocess, which is partly 'manual and partly mechanical, is hereinafter more fully described in connection with the-accompanying drawings, and the different steps in process fully explained.

in drawings, Fig. 1 is a view illustrating an inflated ball to be covered; Fig. 2 is a plan :01" one of the two sections 'of. the cover; Fig. .3 a view of, the ball the cover ipreliminartly -niaced thereon; vFig. 4. is :a plan partly broken away of onset: the molding members; .535

a section separated and partly broken away through the two members of the cover applying mold, the plane of :the section being indicated by the line 5'5:on--Eig.1e; Fig. 6 isan enlarged iragmentary section of cooperating portions "of the two mold membersa vacuum having been applied to draw the rubber sheathing into the mo1d-cavities; Fig. -7 is a fragmentary section similar to Fig. 6 but illustrating the .-pre1iminarily=covered ball placed in the cavity and 'the mold members brought together; Fig. 8 is a view similar to 7 illustrating the result after the application of a. vacuum to the space between the ball *and the cover, the ball having expanded gradually from its internalqoressure to fillthe cavity, causing the cover to bgmolded-into .place on the ball; Fig.9 is a viewsimilar to Fig. .8 but illustratesthe application -of =a fluid pressure to the space between the sheaths and the mold cavities while maintaining the vacuumvbetween the ball and the sheath, this rview presses the cover onto the ball; Fig. 1G is a detail in section through one =of the mold cavities showing the -efiect when the mold members-are separated :and the :pressure and vacuum released; F-ig. =11 .is a view of the-covered ball as released -from the mold showing the anplication of .a filling strip to the space between the-coversections 'Eig. -l-2is-a crosssectionof the filling strip, as indicated by the line -l2-=-|.-2 on Fig. :11 but on a-larger-scale.

In carryingvout my :process I cover one-face-of a number of :layers :of melton with air-curing cement. This isa cement which closes the pores of the "melton on that'side and becomes substantially dry in place but is able to eifect a ready adherenceof the cover =to a ball covered with cement of a different character. Out of the cement covered layer 1 cut, with a die, conventional .ngure #8 .pieces as shown (at A Fig. --2. I then stack the figure 3 pieces one above the other with their'edges in alignment and apply air curing cement to such but edges in the usual manner.

I take a center comprising a hollow rubber ball *3, :Fig. :1, whieh is inflated 'by an internal fluid. pressure tothe'degreedesired in the finished ball, "for instance, 42 pounds to the square inch tor a tennis ba-l'l. This inflation may lee-effected by closing the ball in an atmosphere of com-- :pressed air, or by closing it with suitable chemicals in the "interior which react to produce 3 :pressure, or by puncturing the completed ball with aa hypodermic needle and injecting oomnressed zflnid, rail of these practices being com .cmonfinfthe art.

I now place two of the cover members A about the ball B covered with cement with the longitudinal axes of the cover pieces at right angles to each other, but instead of following the usual practice of pressing the cover down by hand throughout its width to the ball, I press it only along two narrow equatorial zones indicated at XX and YY on Fig. 3, taking care that the cover members outside of these zones are free from the ball.

I now place the ball with the two cover members preliminarily attached, as described, in a mold which is submitted to suction to exhaust the air from the space between the exterior of the ball and the interior of the cover members and about the exterior of the cover members. Thereupon the ball with its cover expands into contact with the mold surface by reason of the internal pressure in the ball and this causes the cover to tightly adhere to the ball center forming a'perfect sphere smoothly covered.

' In effecting thev above operation, I prefer to use'such mold members as shown in Figs. 4 to ln'inclusive, which I will now describe.

In Figs. 4 and 5, I show a pair of suitable plates In, each having a number of mold cavities i i, of approximately hemispherical shape, five rows of five cavities each being indicated in these figures. Each cavity has a vent l2 at its bottom, connecting it with suitable conduits M, which lead to a common conduit to which an exhausting hose l5 may be attached to exhaust all of the cavities.

Extending'across all of the cavities in each mold member is a sheet of vulcanized rubber it, held at its margin to the mold member. I have shown the marginal edges as being bent into a groove l1 surrounding the set of mold cavities and I place a suitable metal frame IS in this groove, over the margins of the rubber sheet IS,

and secure it by screws, one of which is shown at [9 in Fig. 10.

When the air is exhausted from the cavities of the mold through the conduit 15, the rubber sheet l6 becomes seated in each of the cavities forming a lining therefor, as indicated in Fig. 6. These members In with their rubber lined cavities constitute the mold in which I place the balls with the covers preliminarily attached as in Fig.

3, one of such balls being shown in Fig. '7 entrapped between the two mold members [0.

Before bringing the mold members to ether, I place an exhausting tube 20 in the region between them, the ends of such tube being clamped between the two rubber sheets I 6 on the inner side of the annular securing members I3, as shown in Fig. 7. The cavities in each mold member are connected at the face of the mold by grooves l3 and the rubber sheet l6 sinks into these grooves thus providing a tubular connection between successive r-ubber lined cavities, as indicated in Fig. 8. The exhausting conduit 2!! is thus in communication with each of the rubber lined cavities.

I now apply suction to the conduit 21! exhausting the air from all of the lined cavities so that the air is exhausted not only from outside the cover but from the unattached regions between the covers and ball. The exhaustionof this surrounding air in the cavities results in the internal pressure in the ball expanding it so that ts cover comes snugly into engagement with the rubber wall of the cavity, as shown in Fig. 8. This forces the cover throughout its width snugly against the ball center and causes its adherence while the exterior of the cover is maintained in smooth condition by the pressure against the lining of the cavity.

The action of exhausting the air between the marginal portions of the cover and the ball results in a firmer securing of the cover to the ball than in the usual hand operation, and the expansion of the ball by its internal pressure against the rubber lined cavities causes the exterior of the cover to be perfectly spherical and have a smooth exterior.

It is to be understood that the cement em ployed on the inner face of the cover and the exterior of the ball is of the so-called migratory character. That is to say, the cement on the cover is of one composition and the cement on the ball of a diiferent composition and one of them needs to receive something from the other to enable it to acquire sufiicient adhering characteristics. I use on the cover a cement which in itself will not become vulcanized rubber, as it has no vulcanizing agent in it. As the covers are not always immediately used after being coated with cement and cut into figure 8-shapes, the solvent will evaporate but the rubber will not become vulcanized and will remain sticky. The cement used on the ball has an excess of vulcanizing agent mixed in it and provides the amount required to vulcanize the rubber film left on the cover when it comes in contact with it. The result is that I handle both the cover and the ball, each with their applied cements, in a satisfactory manner, but when the cover is firmly pressed on the ball, the cements unite and become vulcanized and form an effective union.

If desired, to obtain a greater pressure in seating the cover than that furnished by the internal pressure of the ball itself, I may readily efiect this by turning off the suction to the passageways i2 which have held the rubber lining in the mold and in place thereof supplying compressed air to such passageways which thereupon forces the lining positively against the exterior of the melton cover, pressing it with increased firmness against the ball.

I now open the conduit from the passages 12 so that the space between the bottoms of the cavities in the mold. members It and rubber linings is open to the atmosphere, th-us freeing the linings from the cavities. I then separate the mold members whereupon the entirely freed lining springs back by its own elasticity into its original planular condition supporting the balls above the cavities as shown in Fig. 10. This may complete the ball, or may complete it except for an 8 shaped groove C between the ad jacent edges of the two cover members.

In attaching the cover to the ball there is an advantage in leaving a narrow space between the edges of the B-shaped members, as it provides a channel adapted to receive excess of cement which is likely to accumulate on the edges of the fl-shaped pieces when they are stacked and cemented.

If no groove between the cover members is desired, I make the cover members of full size, so that their edges actually abut when they are in place on the ball, or a narrow groove may be left open between the applied covers if desired. I prefer, however, to leave a groove of substantial width as shown for instance at C in Figs. 8 to 11, and thereafter fill it by the application of a filling strip, as about to be described.

To fill the groove C, I may employ a rubber strip D cemented to both the ball center and enemas the ledges of' the covers. l hlsrstrip a longi 'tudinaily straight member but in (cross section, is preferably formed as shown in-Fig. F12. is -to say, it 'has a substantially rflatlbottom d, a grooved topapor tion d" and slightly inclined sides d-- 2. Such :a member may be made by ext-rus'ioniandrcoiled for use.

When such a strip, as shown, is "placed inzthe groove 10 between the edges of the 1ne1t0n .xthe base is firmly :attachedttoithe halLJthe inclined edges iii-2 :abut and slightlyiimiierhangzthe edges or .the cover, while the groove I'd :is.=on the-"extemmt;

fitter Fthis :groove strip .13 has :been :placed in the groove (between "the :cover membersand pressed: firmly into place, the, rhallzis submitted than air :nure :crother :means :Qf completing :the vulcanization :off :the acernent and vthus the nirfished rhalll is produced. :The groove ad :in the applied strip gives to finished ball the :.de sired neccssibetwcen 'tcovers, familiar tote-nnis' znl ayers, and is usefiul inypreserving the =ac curacy of the ball :as it moves tluough the air int-response to theplayerisstroke.

,PIn then-old practice, when the ball was milcanized :against the surface :of :a metal mold, the coversurface would flatten sown flush with the top of the cement in 'thegroove between thecow erszand then after t-hesur-face was given a iiufh mg treatment to restore it the space above the exposed cement :became an externally facing l-gltoove hetween the icotver edges. Players have considered that this groove @wasan advantage in the: ball, giving it .a sort (of ri-fiing, "causing .it to Siollow :more accurately the intended course, but when the fluff raised :in the :final treatment of the ball was worn down the groove ceased to exist and its rifiing efiect was lost, which some ,lplaye'rs claim results in the ball f-floating during rplay rather than following its .true course. With my system of furnishing a seam groove extending slower the normal surface of the covers independently-of any temporary fiufiltheremi, I'Emaintain the rifiing groovesefiectiue ,for a much longer nperiodthansvith the roldrhandmethe rod ofwmanufacture.

My-applied strip D gives the depressed seam mark desired .by players but .invva .more regular and smoother form-than where suchldepresse'd seam is bounded merely by the edges .of the meiton covering. Another advantage ofmy applied seam-member is that it may, if. desired, he of a contrasting color to the cover and rthusinrn'ish .aiusefu-l identification marlcfor the user or trade- .nmirlcforthetmanufacturer.

:In the usual method of applying covers by Ehand, the :face vand the edges of the :covers are WBH'IQOVSIGG with vulcanizable cement, so that {the covers are frnbberined at :the edges and-on acme surface, and "in app-lying such a cover .to :the surface. of 17218 "ball in the ordinary method, thene is great danger zthatair will .be entrapped xbetween'the cover (and ball andsealed therein by the :adherence of the edges of the cover {#40 the :bail. This air remains in the ballsand tends to inosen the cover in certain :spots. By any method :ofrwithdrawingcfithe airfrom between the cover and the -cemented surface :Qf the hall while attaching the cover to the. surfaces-covers are :a*-

itached uniformly throughout, lthussgiving a ts-more accurate ball and one with longer life.

By avoiding pressing the cover against a metal surface tosmoothzit asfiiasibeen the custom heretofore, I maintain the cover with its original flufied surface and I- avoidthe necessity for subsequent treatment to :up the rmaztteii cover. '-It has not been practicable :heretoilore with 'a hand applied cover :to employ :drying cement because :it was necessaryito iron out the roughly applieduscover, and this was effected :by using the usual vulcanizable cement :and slibmitting the ball to this external hotzironing operation. With any method, however, :of applying the covers no ironing operationis necessarysand I may thus use an air curing tcemerrtlandisavoid the ironingoperation altogether.

Of course, if desired, one .cou1d use. my=;operation of exhausting the air b'etween theqcovere'anfl' ball and employ vulcanizable cement randsthmit the completed ball 'to vulcanizing heat, but as such operation 'is :unnecessary in my method, for the purpose of ironing out the cover, 1 prefer to :avoid it altogether and thus avoid .the necessity ic-r subsequent treatment to iluffiupithe cover. There is also a savingin'thermeltonby my method because the covers need :not :be 501113 with a fullness to allow for shrinkage which ih'as heretofore resulted from the heat vulcanization of'the'ball.

'When the ordinary ball which requireswulcanization is to be covered by "this apparatus and method, a cement requiring heat to vulcanize such cement is used both on the cover and the ball, as is now done in making the regular ball. When this method andapparatus'is used to snake the present tyne ball, there is gained by iit' e'fliciency in covering by eliminating the handlebor and "there is the further aiivan'ta'geithat the air is Withdrawn from between the cover and the ball when "the cover is attached andlthere will be no air pockets formed by trapping air between two rubber surf-aces, as does often resu'lt inthe ordinary joining of any two sheets of :cemen'ted material'or rubberized surfaces.

"I have referred to using cement of migratory character for uniting the cover to the ball; I find it satisfactory to use on the ball a cement containing 'butyl (which is a very strong accelerato'r) and focusing on the covera cement without 'butyl. There is suflicient "butyl in the acement on'the ball so that some of it "passes to the cover as the cover comes incontact withthe surface of the ball. I prefer to use enoughrcement on the ball so that some oiit sque'ezestout beyond the edge portionoi'the covers as the can is expanded by pressure over the entire "surface, and this allows the covers to shiftn 'littlecin the event that the cover accidentaly adheres-"to the ball beyond the line of pressure .made by the wheels.

The ball made by this entire method; 'usinga cement to attach the .cover that does :not have 'to beyulcanized, and accurately positioning :the covers on the bail and exhausting the from between the covers and the cemented :ba-llfand swelling the ball against the covers-exerting-addition'al pressure against the covers, if desired, and squeezing the ball back to the origina l size carrying with "it the cover, produces economically a very satisfactory'ball. Such method avoidsany -wrinkling of the cover or trapping of air'between the cover'and the "call, and avoids the' result'of matting down the melton cover by heat and pressure during vulcanization and the necessity' 'of again remapping 1311611811301 the cover. My operation not only makes a hetterwearing cover, Ebut much iaster and more accurately and nti-less --expense "than can he done :by hand, as insea the practice heretofore. Reference is made to my divisional applications filed June 7, 1946, Ser. No. 675,052, now abandoned, for claims on the covered ball and Ser. No. 675,053, for claims on the apparatus, herein illustrated and described.

I claim:

1. The method of securing covers on a gas inflated resilient ball having an internal pressure greater than atmospheric pressure, comprising securing a part only of the surface of a cover to the ball leaving a portion of the cover adjacent the edge thereof spaced from the ball, thereafter seating the ball in a mold, and expanding the ball by exhausting the air from the space between the ball and the wall of the mold cavity to below atmospheric pressure to thereby force all regions of 'the cover into intimate contact with the ball.

2. The method of securing covers on a gas inflated resilient ball having an internal pressure greater than atmospheric pressure, comprising securing part only of the surface of a cover to the ball, seating the ball in a mold having a cavity larger than the covered ball, reducing the air pressure between the wall of the cavity and the ball to below atmospheric pressure to cause the ball to expand and squeeze the cover between the wall of the ball and the mold.

3. The method of securing a pair of substantially B-shaped cover members on a gas inflated resilient ball having an internal pressure greater than atmospheric pressure, comprising securing part of the surface of a cover to the ball leaving a portion of the cover adjacent the edge thereof spaced from the ball with an interposed layer of cement, thereafter seating the ball in a mold having a cavity larger than the covered ball, and expanding the ball by exhausting the air from the space between the ball and the wall of the mold cavity to below atmospheric pressure and thereby squeeze the cover members between the wall of the ball and the mold.

4. The method of securing a pair of substantially B-shaped cover members on a gas inflated resilient ball, comprising preliminarily securing the cover members to the ball on narrow equatorial zones at right angles to each other while leaving the remainder of the cover members spaced from but over-laying the surface of the ball, seating the ball in a mold cavity of sufficient size to readily receive the preliminarily covered ball without disturbing the relation of the cover to the ball, expanding the ball and removing the air from between the cover members and the ball by exhausting the air from the space between the ball and the wall of the mold cavity to below atmospheric pressure to cause all portions of the cover to be squeezed between the wall of the mold and the ball thereby affixing the cover to the ball, and subsequently restoring atmospheric pressure to the exterior of the ball to shrink the covered ball to its normal size.

5. The method of sec ring a cover on a gas inflated resilient ball, comprising preliminarily securing a part only of the surface of a cover to the ball while leaving the major portion of the cover spaced from but overlaying the surface of the ball, seating the ball in a mold cavity of sufficient size to readily receive the preliminarily covered ball without materially disturbing the relation of the cover to the ball, expanding the bail by exhausting the air from the space between the ball and the wall of the mold cavity to below atmospheric pressure to cause all portions of the cover to be squeezed between the wall of the mold and the ball thereby aflixing the cover to the ball, and subsequently restoring atmospheric pressure to the exterior of the ball to shrink the covered ball to its normal size.

6. The method of securing covers on a gas inflated expansible ball having an internal pressure greater than atmospheric pressure, comprising securing a part only of the surface of a cover to the ball, seating the ball in a mold cavity having a yielding lining which when drawn into contact with the wall of the mold cavity has a larger diameter than the covered ball, exhausting the air from between the lining and the mold and from between the ball and the lining to cause the ball to expand into contact with the lining as a result of internal pressure in the ball, and thereafter applying fluid pressure between the lining and the wall of the mold to increase the pressure between the lining and the ball.

'7. The method of securing a pair of 8-shaped cover members on a gas inflated resilient ball having an internal pressure greater than atmospheric pressure, comprising preliminarily securing a part'only of the surface of a cover member to the ball with an intermediate layer of cement, seating the ball in a substantially spherical mold cavity having a yielding lining which when drawn into contact with the wall of the mold cavity has an internal diameter of sufficient size to receive the preliminarily covered ball without disturbing the relation of the cover members to the ball, expanding the ball by exhausting the air from between the lining and the mold and from between the ball and the lining, and thereafter applying fluid pressure between the lining and the wall of the mold to increase the pressure between the lining and the ball to squeeze the ball back to its original size carrying the cover with it.

8. The method of applying shrinkable fabric cover members to inflated expansible ball members to provide a tennis ball, comprising forming cover members having a surface area larger than the surface area of the ball member to be covered, coating one of said members with an air curable cement, reducing the pressure around the exterior of the ball to sub-atmospheric to cause the ball to expand, pressing the cover on the ball while so expanded, and thereafter relieving the sub-atmospheric pressure to cause the ball and cover to simultaneously shrink to their normal state.

9. The method of applying a pair of 8-shaped shrinkable fabric cover members to an inflated expansible ball member to provide a tennis ball, comprising forming cover members having a surface area larger than the surface area of the ball member to be covered, coating one of said members with an air curable cement, preliminarily attaching the cover members to the ball by securing a part only of the cover members thereto, placing the preliminarily covered ball in a mold having a substantially spherical mold cavity of a diameter larger than the preliminarily coveredball, reducing the pressure between the wall of the cavity and the ball to sub-atmospheric to cause the ball to expand and press the cover between the ball and the mold cavity while the ball is expanded, and thereafter relieving the sub-atmospheric pressure to cause the ball and cover to simultaneously shrink to their normal state.

FRED THOMAS ROBERTS.

(References on following page) 10 REFERENCES CITED Number Name Date The following references are of record in the 2018559 Homer 1935 file of t t 2,11 ,183 TubbS Mar. 3, 1938 2,210,954 Roberts Aug. 13, 1940 UNITED STATES PATENTS 5 2,211,028 Roberts Aug. 13, 1940 Number Name Date 4,363 Voit et a1 Dec. 10, 1940 1,387,805 Roberts Aug. 16, 1921 2,294,424 Rob rts Sept. 1, 1942 1,415,438 Gibbons May 9, 1922 ,300,096 Bowers Oct. 27, 1942 1,446,885 DeGowin Feb. 27, 1923 309,865 Reach Feb. 2, 1943 1,593,211 Faulkner et a1 July 20, 1926 1 

